#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#include <string.h>

int main() {
    char ch1[1000] = { 0 };
    int i = 0;
    int j = 0;
    scanf("%s", ch1);
    int len = strlen(ch1);
    for (i = 0; i < len - 1; i++)
    {
        for (j = i + 1; j < len; j++)
        {
            if (ch1[j] < ch1[i])
            {
                char tmp = ch1[i];
                ch1[i] = ch1[j];
                ch1[j] = tmp;
            }
        }
    }
    printf("%s", ch1);
    return 0;
}